The present invention relates to a process for the disposal of hydrocarbon-containing and/or halogenated waste products.
It is known how to dispose of hydrocarbon-containing and/or halogenated waste products by incinerating them at high temperature in an open flame and utilizing the energy obtained from this.
Unfortunately, during the incineration of hydrocarbon-containing and/or halogenated waste products a large number of different reaction products are obtained which are questionable in varying degrees as regards their environmental compatibility.
EP-A-0 592 057 discloses a process for the pyrolysis of organic waste substances, preferably of used vehicle tyres, and an apparatus for carrying out the process. The pyrolysis takes place with the exclusion of air and water and is operated under reduced pressure, preferably in a metal bath, at an operating temperature of 450-550xc2x0 C., preferably below 500xc2x0 C.
There is known from US-A-3 252 773 a process for producing hydrogen-containing gas from carbon-containing solid, in which the carbon-containing solid, a copper-containing catalyst and water vapour are brought into contact with an alkali metal melt, under conditions in which hydrogen-rich gas is produced. This gas formation is carried out in a temperature range of 427 to 982xc2x0 C.
The object of the present invention is to develop a process which makes it possible to dispose of various hydrocarbon-containing and/or halogenated waste products in an environmentally friendly manner.
This object is achieved according to the invention by a process for the disposal of hydrocarbon-containing and/or halogenated waste products in which the waste products are reacted with the exclusion of oxygen and humidity in a hydroxide melt at temperatures from 580 to 900xc2x0 C.
In an advantageous embodiment of the process the hydroxide is selected from the group of the alkali hydroxides.
In a preferred manner the hydroxide is sodium hydroxide and/or potassium hydroxide.
In a specific embodiment variant of the process according to the invention the ratio between sodium hydroxide and potassium hydroxide lies between 1:0 and 1:10 and preferably amounts to 1:0.5.
In a preferred embodiment of the process there are formed mainly hydrogen, methane and carbonates and, if halogenated waste products have been used, additionally also metal chlorides.
In addition, metal hydrides can also be obtained during the process, and in certain. cases still further hydrocarbons.
The alkali hydride obtained requires careful handling, since it is extremely reactive.
In order to eliminate alkali hydrides from the gas, preferably an alkali hydroxide melt or else a hydrocarbon is used.
The alkali hydrides obtained can be used either for obtaining metals or for obtaining hydrogen. The alkali hydroxides thereby obtained can be returned into the process.
Whereas the formation of alkali metal compounds is promoted in the temperature range around 300xc2x0 C.-500xc2x0 C., the maximum for hydrogen obtainable in the gaseous state lies at about 580xc2x0 C. to about 900xc2x0 C.
There can be used as hydrocarbon-containing waste products solvents, tars, spent oils, lubricants, fats, paints, dyes, waxes and non-halogenated plastics such as polyethylene, polypropylene, polystyrenes, polycarbonates or rubber, and as halogenated waste substances solvents such as chloroform, methylene chloride, tetra- and trichloroethylene, tetrachloroethane, coolants and refrigerants (CFCs), PCBs, dioxins, furans, brake fluid, pesticides, fungicides and herbicides, halogenated plastics.
The melt can furthermore contain a catalyst which contains a metal oxide not reducible by sodium hydride and which, if possible, is resistant to sulphur and/or sulphur compounds.
The reaction substances are preferably chosen from materials which do not form metallates with alkali hydrides and if possible also do not form any metal carbonyls, or only to a small extent.